deletions | additions       diff --git a/Methodology Measurements TTC.tex b/Methodology Measurements TTC.tex  index bd5ca62..011bfbe 100644  --- a/Methodology Measurements TTC.tex  +++ b/Methodology Measurements TTC.tex 
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Time-to-collision is measured instantaneously: a new value of TTC may be computed for every interaction-instant. Thus, a pair of users may have a time series of TTC observations evolving over time. Some efforts have been made to study these evolutions \cite{Mohamed_2013}. Other approaches have focused on quantile or threshold observations \cite{Svensson_2006}, while others still attempt to examine instantaneous risk and significance of TTC.  TTC distributions are generally gamma-like-shaped across the literature. literature \cite{Ismail_2010} \cite{Autey_2012} \cite{St_Aubin_2013}.  Quantifying collision risk based on TTC is the remaining puzzle piece. TTC thresholds have been popular, though are subject to arbitrary selection. One recent approach proposed a shifted gamma-generalised pareto distribution model \cite{Zheng_2014}. In the meantime, some qualitative analysis is possible in some circumstances, for example when shifts in center of mass of distributions are clear as demonstrated in Figure~\ref{fig:distro-comparison}. This approach has been tried in some early applications of the methodology, e.g. in \cite{Autey_2012} \cite{Ismail_2010}, \cite{Autey_2012},  and in \cite{St_Aubin_2013}.